This section provides background information related to the present disclosure and is not necessarily prior art.
In an effort to quiet vehicle interiors, vehicles such as automobiles are commonly equipped with acoustic mats placed along one or more walls of the vehicle. Acoustic mats are constructed of materials that absorb noise and vibration and/or materials that block the transmission of noise and vibration through the acoustic mat. While such acoustic mats perform well over uninterrupted areas of a vehicle wall, acoustic performance is drastically reduced in areas where electrical wiring harnesses or other penetrating components pass-through openings in the vehicle wall and thus the acoustic mat. Such openings are prolific in most vehicle firewalls, which are typically a sheet metal wall disposed between an engine compartment and a passenger compartment of a vehicle. Wall openings pose additional problems because water and dust can travel through these spaces. Chaffing of the electrical wiring harness or other penetrating components can also occur in the vicinity of wall openings. Accordingly, grommets are commonly used where electrical wiring harnesses or other penetrating components pass-through the openings in a vehicle wall.
Grommets typically include an annular groove or channel that is disposed along an outer circumference of the grommet. This annular channel or recess either engages the sheet metal surrounding the wall opening or portions of the acoustic mat adjacent the wall opening. For example, U.S. Pat. No. 8,314,337 which issued to Fujita on Nov. 20, 2012 discloses an electrical wiring grommet that includes an annular groove for engaging the sheet metal surrounding a through hole in a vehicle body. In another example, U.S. Pat. No. 6,941,714 which issued to Nakamura on Sep. 13, 2005 discloses an electrical wiring grommet that includes an annular groove for engaging one of the layers of an acoustic mat. Such grommets can be problematic because they are prone to faulty installation.
Typically, grommets are installed by hand, where an installer pushes part of the grommet through the appropriate opening or hole in the vehicle wall and/or acoustic mat. The installer is supposed to continue pushing the grommet through the opening until the sheet metal surrounding the opening in the wall is received in the annular groove or until a layer of the acoustic mat is received in the annular groove. Oftentimes however, the installer does not fully install the grommet either due to inattention or because it is difficult to determine whether or not proper seating has occurred. In the later instance, the grommet may be located in an area where access is limited, making visual inspection difficult. Also, the arrangement of the annular groove or channel may not provide significant tactile feedback to the installer to indicate that the grommet has been properly installed. This is particularly common where the acoustic mat or portions thereof locks into the annular groove in the grommet because acoustic mats are often flexible themselves, making installation of the grommet more difficult. Ultimately, poorly installed grommets have poor acoustic performance, can provide leak pathways for water and dust, and are prone to fall away from the opening completely during the service life of the vehicle.